Coloring-matter for leather and method of using the same



No Drawing.

UNITED STATES PATENT OFFICE.

JOHN H. rrmes'rnn, or MILWAUKEE, WISCONSIN, ASSIGNOR TO PRESTO COLORCOMP OF GUDAHY, DNSlN, A CORPORATION OF wIsooNsm.

COLORING-MATTER FOR LEATHER AN D METHOD OF USING THE SAME.

' oring matter which, while being permanent .by boiling;

carried on at certain temperatures,

and non-fading, can be quickly and cheaply applied to leather withoutthe necessity of boiling and'use of mordants, etc., and which gives auniformity of colorand economy of operation beyond that which hashitherto been known.

Leather has heretofore been colored by dyeing with various kinds of dyessuch as logwood, fustic, cochineal, and of late more particularly theso-called anilin dyes or coal-tar 'dyes. The use of dyes of thischaracter is open to the following objections: They must be previouslydissolved in water, ordinarily the leather tobe dyed must be speciallytreated before dyeing to prepare it for the dye; the use of mordants toobtain satisfactory results is in every case practically essential; thedyeing must (pe or 1- narily close to boiling point; in most cases acertain amount of acid must be used which has a deleterious effect uponthe fiber of the leather; and in no case can all of the dye stuff heused, a considerable amount necessarily remaining in solution in thewater. Further than this, it has been impossible to dye different runsof leather to exactly the same shade by means of dye stuffs which areheld in solution without repeated tonings up so as to match the shades.Thus for example, in making a chocolate color by means.

of coal-tar dyes it requires expert work to produce uniformity ofshade,.as many as twenty shades of chocolate being produced from thesame run of dye unless great care is taken.

All of the dye stufi's heretofore used, so far as I am aware, operateupon the principle of their being dissolved in water and thenprecipitated out upon the fibers of the leather by chemical actiongenerally aided by the mordant or heat, or both. I have Specification ofLetters Patent.

Patented Mar. 15, 1921.

Application filed July 2, 1917. Serial No. 178,287.

discovered, however, that by making a colormg matter of finely dividedinsoluble pigment, suspend ng it in a fluid and then agitating theleather to be colored and the fluid with respect to each other, I amenabled to deposit the pulverulent pigment in the interstices of theleather, thus producing a permanent, definite color thereon which willnot fade or crock, and at the same time using up all ofthe coloringmatter. When my new colorlng matter and process are used I can color alarge number of pieces of leather at one time, produce a uniform shadeon each of them, and use up all of the coloring matter, the fluid inwhich it had been suspended, upon being drawn off after the operationbeing substantially colorless. It is, however, necessary in order thatmy colormg matter and process give satisfactory resultsthat the leatherto which they are to be applied be porous, z. e., it must either be aspllt or sufficient of the grain must be buffed off so that the coloringmatter can enter into and find lodgment in the pores of the leather. Myprocess is quite different from pa nting on leather, in that whenleather is palnted the surface only is coated and the plgment 1s causedto stick to the leather by chemical changes, principally oxidation ofthe oils, and the leather is rendered stiff and hard. In my process theleather is neither painted nor dyed as those words are ordinarily used,but the finely divided coloring matter is forced into and intimatelyheld in the reticulations-in the leather, which is left soft andpliable,

A preferred form of my new coloring matter is produced as follows: Ihave selected by way of specific illustration a chocolate color becauseof the difiiculty in the past of producing uniformity of shade therein,but it is to be understood that I am not limiting m self to theproduction of that color, as reserve the right to vary the colors and inredients within the scope of the appended c aims. To produce a chocolatecolor I take the following earthy pigments such as are commonly used inthe painting art: Six pounds burnt sienna, eight pounds Indian red, fourpounds burnt" umber, one and three-quarter pounds yellow ocher,one-fourth pound lamp black, total twenty pounds. These ingredients arethen finely pulverized in an ordinary paint grinder or pugging milluntil they will go 1 through a mesh of fifty to the inch. The moreuniformthe grinding and the finer divided the resultant product thebetter results will be obtained.

In case the leather contains an excess of fat I may at my option add asmall amount of soda ash, sodium bicarbonate or other al-' kali so as toremove the-excess of fat. Thus, if the stock has been fat liquored I mayadd about four per cent. by weight of soda ash to the pigments abovementioned.

This product is dry, comparatively cheap, easily portable, and is notaifected by time, changes in climatic conditions, etc., neither do thecolors-.that it makes crock or fade on exposure to light.

In order to apply my improved color I suspend it in a fluid and agitateeither the fluid or the leather therein. In my preferred form I take theleather, which as previously stated, must be porous, wash it twentyminutes in water of a temperature of 150 to 175 degrees F. in arevolving drum. The drum I use is six feet wide and eight feet high,outside dimensions, and rotates between 16 and 20B. P. M., althou h anysuitable apparatus can be used. ireferably the leather has beenpreviously fat liquored and dried. I then throw into the drum a batch ofmy improved'color made up as aforesaid, z. 6., approximately 21 poundsthereof, and continue the. revolutions of the drumfor about twentyminutes. The Water is then drawn off, the leather removed and dried. Onrunning off the water it will be found that substantially all of thecoloring matter is removed there from, the water being substantiallycolorless, and the coloring matter will be found to have uniformlycolored the leather by physical penetration intothe interstices thereofso as to form a uniform, permanent color thereon. Aside from the effectof the alkali actin upon the grease in the leather and saponi ying it(and which is purely optional), I know of no chemical when in myprocess; it is purely a physical penetrating coloring incontradistinction to chemical dyeing and surface painting as haveheretofore been practised. i

I do not want to be understood as limiting myself to the use of theparticular pigments heretofore referred to as I can use any pigment thatis insoluble in water, but which when finely pulverized can be suspendedtherein by agitation. Neither do I desire to limit myself to the use ofwater as the fluid medium for practising my process as other media suchas air may be substituted therefor.

Having fully described my invention, 1 claim:

1. A coloring matter suitable for coloring leather by suspension in afluid and consisting of pulverulent pigment insoluble in said fluid andcontaining approximately four per cent. by weight of sodium bicarbonate.

2. A process of coloring leather which consists in suspendingpulverulent, insoluble leather therein in the presence of heat so thatthe pigment is uniformly deposited in the interstices of the leather,and the excess of fat saponified.

In testimony whereof I hereunto aflix my signature in the presence oftwo witnesses.

' JOHN H. PFINGSTEN Witnesses:

' E. HELMLoF,

N. R. HELMLOF.

